Formal Verification by Reverse Synthesis

Using dynamic analysis to discover polynomial and array invariants

“…The manual annotation of AES with sufficient invariants to admit machine-checked full formal verification was a significant undertaking involving hours of tool-assisted manual effort [25], [26]. Annotating pre-and postconditions and loop invariants has not been solved in general and is known to be a key bottleneck in approaches based on axiomatic semantics [27].…”

Exploiting refactoring in formal verification

“…This technique rests on the hypothesis that the high-level architectural information in a specification is frequently retained in the implementation. We have no experimental evidence to support this hypothesis, but our rationale for believing it is discussed in an earlier paper [17].…”

“…Echo uses several techniques to synthesize this specification [17], but the key in Echo to making the proof practical lies in a technique that we refer to as architectural and direct mapping. This technique rests on the hypothesis that the high-level architectural information in a specification is frequently retained in the implementation.…”

“…In previous work [17], we conducted a study of the general feasibility of an earlier version of Echo in which we verified only part of AES. In the work described here, we verified the functional correctness of the complete AES implementation.…”

“…In previous work, we introduced the Echo approach to formal verification [14,17]. The goal that we have for Echo is to make formal verification of software more practical.…”